A machine is supplied energy at a rate of 4,000 W and does useful work at a rate of 3,760 W. What is the efficiency of the machine?
a. 92 percent
b. 94 percent
c. 96 percent
d. 97 percent?
The efficiency of the machine can be found by dividing the useful work by the supplied energy.
Machines and Mechanics
1. A 0.100 kg meterstick is supported at its 40.0 cm mark by a string attached to the ceiling. A 0.700 kg mass hangs vertically from the 5.00 cm mark. A mass is attached somewhere on the meterstick to keep it horizontal and in both rotational and translational equilibrium. If the force applied by the string attaching the meterstick to the ceiling is 19.6 N, determine the following:
a. the value of the unknown mass
b. the point where the mass attaches to the stick
2. The efficiency of a squeaky pulley system is 73 percent. The pulleys are used to raise a mass to a certain height. What force is exerted on the machine if a rope is pulled 18.0 m in order to raise a 58 kg mass a height of 3.0 m?
3. A person lifts a 950 N box by pushing it up an incline. If the person exerts a force of 350 N along the incline, what is the mechanical advantage of the incline?View Full Posting Details